Had a guy riding a Harley do that to me once in Dallas of all places. He was in the far left lane and cut strongly across to get in front of me in the far right lane. We were in stop and go for a few minutes. Then at one go point he hit his brakes right after starting to move. Caused me to slam the brakes after stating to move and barely miss hitting him. Got the impression he did it on purpose. Of course I was driving a rental car with California plates, so maybe that had something to do with it.
brakes right after starting to move
as a biker did you actually see him brake or in a case I had the bike stalled just as I was starting to move causing me to stop. to which I was able to start again and take off. There were no brake lights till I stopped to restart.